I don't see any reason why you wouldn't be able to get one for $500 at this point, they really are ridiculously cheap. Even a 55" probably wouldn't cost too much more.
I pretty much only use my PS3 as a glorified Blu-ray player, but it's actually good to point out Plasma responsiveness is better for gaming.
In terms of reflections - incredibly reflective. Expect to have to control light in the room (blinds during the day, lights off) you are putting it in, or just learn live with it. Keep in mind any source of light coming from behind the TV isn't a problem, it's whatever is in front of it traveling in it's direction. It can be a major distraction on dark scenes, or in general on black bar content where you are able to see yourself/the room. If you're just watching the news or general TV, it shouldn't be something you notice regardless of the conditions.
Glass is partly what makes it look so vivid and exceptional though, so it's a worthwhile tradeoff in my opinion.